WO2000062118A1 - Adjustable bragg-grating filter module - Google Patents

Adjustable bragg-grating filter module Download PDF

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Publication number
WO2000062118A1
WO2000062118A1 PCT/DE2000/001026 DE0001026W WO0062118A1 WO 2000062118 A1 WO2000062118 A1 WO 2000062118A1 DE 0001026 W DE0001026 W DE 0001026W WO 0062118 A1 WO0062118 A1 WO 0062118A1
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WIPO (PCT)
Prior art keywords
length
bragg filter
filter module
bragg
electronically adjustable
Prior art date
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PCT/DE2000/001026
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German (de)
French (fr)
Inventor
Detlef Stoll
Patrick Leisching
Harald Bock
Alexander Richter
Original Assignee
Siemens Aktiengesellschaft
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Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to DE50000873T priority Critical patent/DE50000873D1/en
Priority to EP00931006A priority patent/EP1166171B1/en
Priority to AU49102/00A priority patent/AU4910200A/en
Publication of WO2000062118A1 publication Critical patent/WO2000062118A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0128—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects
    • G02F1/0131—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence
    • G02F1/0134—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence in optical waveguides
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/011—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  in optical waveguides, not otherwise provided for in this subclass
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/146—External cavity lasers using a fiber as external cavity
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/30—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 grating
    • G02F2201/307—Reflective grating, i.e. Bragg grating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
    • H01S5/0285—Coatings with a controllable reflectivity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon

Definitions

  • Adjustable Bragg grating filter module
  • the invention relates to an electronically adjustable Bragg grating filter module.
  • add-drop modules are used that enable the coupling (drop) and coupling (add) of individual channels or channel groups.
  • add-drop modules can contain tunable fiber Bragg gratings as branching and coupling elements, which act as filters and are briefly referred to as Bragg filters.
  • piezoelectric actuators When using piezoelectric actuators (translators), their expansion is a non-linear function of the applied voltage.
  • piezoelectric elements have a hysteresis behavior in their expansion function.
  • the expansion function is also temperature-dependent.
  • a precise setting is also made more difficult by a mechanical drift movement of the elements.
  • the central frequency of a Bragg filter controlled in this way cannot be adequately controlled.
  • the hysteresis behavior prevents an exact reproducibility of the setting (error between 5 and 10 GHz (gigahertz)).
  • the drift movement leads to an inaccuracy of approximately 3 GHz.
  • add-drop modules constructed with this filter and a suitable one-piece device for controlling them must be specified.
  • An electronically adjustable Bragg filter module is specified in claim 1; a corresponding add-drop module and a dividing device are described in independent claims.
  • the specified filter module With the specified filter module, a very precise measurement of the change in length of the fiber grating is possible, which enables the central frequency to be set with a single calibration of the structure with an accuracy of approximately 1 GHz.
  • An embodiment of the filter module is particularly advantageous, the piezo actuator of which consists of several assembled piezo elements, to which a fiber Bragg grating is firmly bonded.
  • the corresponding filters can be used in all add-drop modules.
  • the filters are set with the help of a control circuit, which uses a signal corresponding to the change in length as a control variable and as a reference variable
  • the desired change in length is supplied, which can be changeable according to the temperature dependence of the length measuring device and the Bragg grating.
  • a known strain gauge is used as the length measuring device, the resistance of which changes with the length.
  • a capacitive strain gauge can be used for higher requirements.
  • FIG. 1 shows a filter module according to the invention
  • FIG. 2 shows an add-drop module constructed with this filter module
  • FIG. 3 shows a control device for this add-drop module.
  • FIG. 1 shows an embodiment of a tunable Bragg filter module FM.
  • a piezo actuator P made up of a plurality of piezo elements 1 arranged in a row is provided. It is controlled via electrical connection lines 5. A change in length of the piezo actuator is achieved by applying different voltages.
  • An optical fiber 2 with a fiber Bragg grating 3 is glued into a groove on the surface. This is produced by a special treatment of the fiber, which is optically denser at defined intervals, so that a certain wavelength (more precisely a certain range) is reflected due to interference processes.
  • the most suitable stretching properties currently have fiber grids, in principle, other e.g. planar Bragg gratings can be used.
  • At least one strain gauge 4 is arranged above the fiber as a length measuring device, the measuring connecting lines 6 of which are connected to a measuring device.
  • several strain gauges can be arranged in a bridge circuit. Depending on the requirements, strain gauges can be used, the resistance or capacitance of which depends on the change in length. According to a table, the length of the piezo actuator and thus the Bragg filter is changed and a desired central frequency (or cutoff frequency) is set.
  • Another strain gauge 14 is provided for temperature compensation.
  • FIG. 2 shows an add-drop module which consists of the series connection of a first circulator 7, three filter modules FM1, FM2, FM3 and a second circulator 9.
  • a wavelength multiplex signal WDM is fed to a first connection of the first circulator. This signal is emitted at a second connection (clockwise), individual channels being reflected by the Bragg filters of the individual filter modules FM1 to FM3 and fed back into the same connection in order to be output as drop channels 8 at the third connection of the circulator .
  • the piezo actuators P are controlled via control voltages U1 to U3 in order to carry out the corresponding central frequency setting of the Bragg filters.
  • Add channels 10, which have the same wavelengths, are fed in via an insertion device, a second circulator 9 (or a directional coupler) and are transmitted together with the switched-through channels as a wavelength division multiplex signal WDM1.
  • FIG. 3 shows a control loop for setting the Bragg filter 3.
  • the central frequency is set with the aid of a setpoint generator 13, to which the setpoint frequency FZ is fed. This converts the target frequency into an electrical reference variable F based on a stored table, the ambient temperature Tu being able to be taken into account.
  • a controlled variable R is compared with the reference variable F in a comparator 11.
  • the controlled variable an electrical voltage, is obtained with the aid of the strain gauge 4 and serves as a measure of the length or change in length of the Bragg filter 3.
  • an adjustment voltage U1 is obtained corresponding to the deviations between the reference variable and the controlled variable Piezo actuator P controls and thus defines the length of the Bragg filter.
  • Non-linearities in the control loop are taken into account by the setpoint generator.
  • an accuracy of 1 GHz can be achieved; More precise length measurements can be achieved with capacitive strain gauges.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Optical Communication System (AREA)

Abstract

The invention relates to an electronically adjustable Bragg-grating filter module (FM) which comprises a piezoelectric actuator (1) with which the length of the Bragg-grating filter (3) can be modified. The change in length of the Bragg-grating filter can be precisely measured by means of a strain gauge (4). Since the centre frequency of the Bragg-grating filter (3) depends on its length this permits an indirect adjustment of the frequency. The above filter is especially suitable for remote-controlled add-drop modules (ADM). To eliminate the influences of the piezoelectric element during adjustment of the Bragg-grating filter frequency adjustment is carried out by means of a regulator circuit.

Description

Beschreibungdescription
Einstellbares Bragg-Gitter-FiltermodulAdjustable Bragg grating filter module
Die Erfindung betrifft ein elektronisch einstellbares Bragg- Gitter-Filtermodul .The invention relates to an electronically adjustable Bragg grating filter module.
In optischen Netzen wird in zunehmendem Maße zur Übertragung die Wellenlängen-Multiplextechnik eingesetzt, bei der mehrere Übertragungskanäle mit unterschiedlichen Wellenlängen verwendet werden. Um Verbindungen zwischen einzelnen Terminals flexibel schalten zu können, man spricht vom flexiblen Routing von Wellenlängenkanälen, werden Add-Drop-Module verwendet, die das Auskoppeln (Drop) und Einkoppeln (Add) einzelner Kanäle oder Kanalgruppen ermöglichen. Diese Add-Drop-Module können als Abzweig- und Einkoppelelemente enthalten abstimmbare Faser-Bragg-Gitter enthalten, die als Filter wirken und kurz als Bragg-Filter bezeichnet werden.In optical networks, wavelength multiplexing is increasingly being used for transmission, in which several transmission channels with different wavelengths are used. In order to be able to switch connections between individual terminals flexibly, one speaks of flexible routing of wavelength channels, add-drop modules are used that enable the coupling (drop) and coupling (add) of individual channels or channel groups. These add-drop modules can contain tunable fiber Bragg gratings as branching and coupling elements, which act as filters and are briefly referred to as Bragg filters.
In Electronics Letters, 8 January 1998, Vol. 34, No. 1, Seite 104 und 105 sind solche Add-Drop-Elemente beschrieben. Die Zentralfrequenz (hier Sperrfrequenz) der als Grätings (Gitter) ausgebildeten Filter kann durch Steuersignale geändert werden.In Electronics Letters, 8 January 1998, Vol. 34, No. 1, pages 104 and 105, such add-drop elements are described. The central frequency (blocking frequency here) of the filters designed as gratings (grating) can be changed by control signals.
Bei der Verwendung von piezoelektrischen Aktoren (Translatoren) ist deren Ausdehnung eine nichtlineare Funktion der angelegten Spannung. Außerdem weisen piezoelektrische Elemente in ihrer Ausdehnungsfunktion ein Hystereseverhalten auf. Die Ausdehungsfunktion ist außerdem temperaturabhängig. Eine genaue Einstellung wird außerdem durch eine mechanische Driftbewegung der Elemente erschwert. Nach einer Veränderung der angelegten Spannung ändert sich die Ausdehnung des Piezoelements trotz konstanter Spannung weiter. Die Zentralfrequenz eines so angesteuerten Bragg-Filters ist hierdurch nicht ausreichend kontrollierbar. Das Hystereseverhalten verhindert eine genaue Reproduzierbarkeit der Einstellung (Fehler zwischen 5 und 10 GHz (Gigahertz) ) . Die Driftbewegung führt zu einer Ungenauigkeit von etwa 3 GHz. Diese Toleranzen sind bei WDM-Syste en (Wellenlängenmultiplex) schwer verkraftbar.When using piezoelectric actuators (translators), their expansion is a non-linear function of the applied voltage. In addition, piezoelectric elements have a hysteresis behavior in their expansion function. The expansion function is also temperature-dependent. A precise setting is also made more difficult by a mechanical drift movement of the elements. After changing the applied voltage, the expansion of the piezo element continues to change despite the constant voltage. As a result, the central frequency of a Bragg filter controlled in this way cannot be adequately controlled. The hysteresis behavior prevents an exact reproducibility of the setting (error between 5 and 10 GHz (gigahertz)). The drift movement leads to an inaccuracy of approximately 3 GHz. These tolerances are difficult to cope with with WDM systems (wavelength division multiplexing).
Aufgabe der Erfindung ist es daher, ein elektronisch einstellbares Bragg-Filtermodul anzugeben, das eine wesentlich genauere Einstellung der Zentralfrequenz ermöglicht. In weiteren Aufgaben sind mit diesem Filter aufgebaute Add-Drop-Module und eine geeignete Einsteileinrichtung zu deren Ansteue- rung anzugeben.It is therefore an object of the invention to provide an electronically adjustable Bragg filter module which enables the central frequency to be set much more precisely. In other tasks, add-drop modules constructed with this filter and a suitable one-piece device for controlling them must be specified.
Ein elektronisch einstellbares Bragg-Filtermodul ist in Anspruch 1 angegeben; ein entsprechendes Add-Drop-Modul und eine Einsteileinrichtung sind in unabhängigen Ansprüchen be- schrieben.An electronically adjustable Bragg filter module is specified in claim 1; a corresponding add-drop module and a dividing device are described in independent claims.
Mit dem angegebenen Filtermodul ist eine sehr genaue Messung der Längenänderung des Fasergitters möglich, die das Einstellen der Zentralfrequenz nach einer einmaligen Eichung des Aufbaus mit etwa 1 GHz Genauigkeit ermöglicht.With the specified filter module, a very precise measurement of the change in length of the fiber grating is possible, which enables the central frequency to be set with a single calibration of the structure with an accuracy of approximately 1 GHz.
Besonders vorteilhaft ist eine Ausführungsform des Filtermoduls, dessen Piezoaktor aus mehreren zusammengefügten Piezo- elementen besteht, mit denen ein Faser-Bragg-Gitter fest ver- klebt ist.An embodiment of the filter module is particularly advantageous, the piezo actuator of which consists of several assembled piezo elements, to which a fiber Bragg grating is firmly bonded.
Die entsprechenden Filter können in allen Add-Drop-Modulen verwendet werden. Die Einstellung der Filter erfolgt mit Hilfe eines Regelkreises, dem als Regelgröße ein der Längen- Veränderung entsprechendes Signal und als FührungsgrößeThe corresponding filters can be used in all add-drop modules. The filters are set with the help of a control circuit, which uses a signal corresponding to the change in length as a control variable and as a reference variable
(Sollwert) die gewünschte Längenänderung zugeführt wird, wobei diese entsprechend der Temperaturabhängigkeit der Längen- messeinrichtung und des Bragg-Gitters veränderbar sein kann. Aus Kostengründen wird als Längenmeßeinrichtung ein bekannter Dehnungsmeßstreifen eingesetzt, dessen Widerstand sich mit der Länge ändert. Bei höheren Anforderungen kann ein kapazitiv wirkender Dehnungsmeßsensor eingesetzt werden. Ein Ausführungsbeispiel der Erfindung wird anhand von Figuren näher erläutert.(Desired value) the desired change in length is supplied, which can be changeable according to the temperature dependence of the length measuring device and the Bragg grating. For cost reasons, a known strain gauge is used as the length measuring device, the resistance of which changes with the length. A capacitive strain gauge can be used for higher requirements. An embodiment of the invention is explained in more detail with reference to figures.
Es zeigen:Show it:
Figur 1 ein erfindungsgemäßes Filtermodul,FIG. 1 shows a filter module according to the invention,
Figur 2 ein mit diesem Filtermodul aufgebautes Add-Drop-Modul und Figur 3 eine Ansteuereinrichtung für dieses Add-Drop-Modul.2 shows an add-drop module constructed with this filter module, and FIG. 3 shows a control device for this add-drop module.
Figur 1 zeigt ein Ausführungsbeispiel eines abstimmbaren Bragg-Filtermoduls FM. Zur Abstimmung des Filters ist ein aus mehreren aneinandergereihten Piezoelementen 1 aufgebauter Piezoaktor P vorgesehen. Die Ansteuerung erfolgt über elektrische Anschlußleitungen 5. Durch Anlegen unterschiedlicher Spannungen wird eine Längenänderung des Piezoaktors erreicht. In einer auf der Oberfläche angebrachten Nut ist eine optische Faser 2 mit einem Faser-Bragg-Gitter 3 eingeklebt. Die- ses wird durch eine spezielle Behandlung der Faser hergestellt, die in definierten Abständen optisch dichter ist, so daß aufgrund von Interferenzvorgängen eine bestimmte Wellenlänge (genauer ein bestimmter Bereich) reflektiert wird. Die geeignetsten Dehnungseigenschaften besitzen derzeit Faser- Gitter, prinzipiell können auch andere z.B. planar ausgeführte Bragg-Gitter verwendet werden.Figure 1 shows an embodiment of a tunable Bragg filter module FM. To tune the filter, a piezo actuator P made up of a plurality of piezo elements 1 arranged in a row is provided. It is controlled via electrical connection lines 5. A change in length of the piezo actuator is achieved by applying different voltages. An optical fiber 2 with a fiber Bragg grating 3 is glued into a groove on the surface. This is produced by a special treatment of the fiber, which is optically denser at defined intervals, so that a certain wavelength (more precisely a certain range) is reflected due to interference processes. The most suitable stretching properties currently have fiber grids, in principle, other e.g. planar Bragg gratings can be used.
Über der Faser ist als Längenmeßeinrichtung mindestens ein Dehnungsmeßstreifen 4 angeordnet, dessen Meßanschlußleitungen 6 mit einer Meßeinrichtung verbunden werden. Zur Temperaturkompensation können mehrere Dehnungsmeßstreifen in einer Brückenschaltung angeordnet werden. Je nach Anforderungen können Dehnungsmeßsensor verwendet werden, deren Widerstand oder Kapazität von der Längenänderung abhängig ist. Entspre- chend einer Tabelle wird die Länge des Piezoaktors und damit des Bragg-Filters geändert und so eine gewünschte Zentralfrequenz (oder Grenzfrequenz) eingestellt. Ein weiterer Dehnungsmeßstreifen 14 ist zur Temperaturkompensation vorgesehen.At least one strain gauge 4 is arranged above the fiber as a length measuring device, the measuring connecting lines 6 of which are connected to a measuring device. For temperature compensation, several strain gauges can be arranged in a bridge circuit. Depending on the requirements, strain gauges can be used, the resistance or capacitance of which depends on the change in length. According to a table, the length of the piezo actuator and thus the Bragg filter is changed and a desired central frequency (or cutoff frequency) is set. Another strain gauge 14 is provided for temperature compensation.
In Figur 2 ist ein Add-Drop-Modul dargestellt, das aus der Reihenschaltung eines ersten Zirkulators 7, dreier Filtermodule FM1, FM2, FM3 und einem zweiten Zirkulator 9 besteht. Einem ersten Anschluß des ersten Zirkulators wird ein Wellen- längen-Multiplexsignal WDM zugeführt. Dieses Signal wird an einem zweiten Anschluß (im Uhrzeigersinn) abgegeben, wobei einzelne Kanäle durch die Bragg-Filter der einzelnen Filtermodule FM1 bis FM3 reflektiert und in denselben Anschluß erneut eingespeist werden, um am dritten Anschluß des Zirkulators als Drop-Kanäle 8 ausgegeben zu werden. Über Steuerspannungen Ul bis U3 werden die Piezoaktoren P angesteuert, um die entsprechende Zentralfrequenz-Einstellung der Bragg-Filter durchzuführen. Add-Kanäle 10, die dieselben Wellenlängen aufweisen, werden über eine Einfügeeinrichtung, einen zweiten Zirkulator 9 (oder einen Richtkoppler) , eingespeist und zusammen mit den durchgeschalteten Kanälen als Wellenlängen- Multiplexsignal WDM1 ausgesendet.FIG. 2 shows an add-drop module which consists of the series connection of a first circulator 7, three filter modules FM1, FM2, FM3 and a second circulator 9. A wavelength multiplex signal WDM is fed to a first connection of the first circulator. This signal is emitted at a second connection (clockwise), individual channels being reflected by the Bragg filters of the individual filter modules FM1 to FM3 and fed back into the same connection in order to be output as drop channels 8 at the third connection of the circulator . The piezo actuators P are controlled via control voltages U1 to U3 in order to carry out the corresponding central frequency setting of the Bragg filters. Add channels 10, which have the same wavelengths, are fed in via an insertion device, a second circulator 9 (or a directional coupler) and are transmitted together with the switched-through channels as a wavelength division multiplex signal WDM1.
In Figur 3 ist ein Regelkreis zur Einstellung des Bragg-Filters 3 dargestellt. Die Zentralfrequenz wird mit Hilfe eines Sollwertgebers 13 eingestellt, dem die Sollfrequenz FZ zuge- führt wird. Dieser setzt die Sollfrequenz aufgrund einer gespeicherten Tabelle in eine elektrische Führungsgröße F um, wobei die Umgebungstemperatur Tu berücksichtigt werden kann. In einem Komparator 11 wird eine Regelgröße R mit der Führungsgröße F vergleichen. Die Regelgröße, eine elektrische Spannung, wird mit Hilfe des Dehnungsmeßstreifens 4 gewonnen und dient als Maß für die Länge bzw. Längenänderung des Bragg-Filters 3. In einem Regler 12 wird entsprechende den Abweichungen zwischen Führungs- und Regelgröße eine Einstellspannung Ul gewonnen, die den Piezoaktor P steuert und damit die Länge des Bragg-Filters festlegt. Nichtlinearitäten im Regelkreis werden durch den Sollwertgeber berücksichtigt. it einem herkömmlichen Dehnungsmeßstreifen ist eine Genauigkeit von 1 GHz erzielbar; genauere Längenmessungen können mit kapazitiven Dehnungsmeßstreifen erzielt werden. FIG. 3 shows a control loop for setting the Bragg filter 3. The central frequency is set with the aid of a setpoint generator 13, to which the setpoint frequency FZ is fed. This converts the target frequency into an electrical reference variable F based on a stored table, the ambient temperature Tu being able to be taken into account. A controlled variable R is compared with the reference variable F in a comparator 11. The controlled variable, an electrical voltage, is obtained with the aid of the strain gauge 4 and serves as a measure of the length or change in length of the Bragg filter 3. In a controller 12, an adjustment voltage U1 is obtained corresponding to the deviations between the reference variable and the controlled variable Piezo actuator P controls and thus defines the length of the Bragg filter. Non-linearities in the control loop are taken into account by the setpoint generator. With a conventional strain gauge, an accuracy of 1 GHz can be achieved; More precise length measurements can be achieved with capacitive strain gauges.

Claims

Patentansprüche claims
1. Elektronisch einstellbarer Bragg-Filtermodul (FM)zur Einstellung der die Länge eines Bragg-Filters (3), dadurch geken zeichnet, daß zur Messung der Länge oder Längenänderung des Bragg-Filters (3) eine Längenmeßeinrichtung (4) vorgesehen ist.1. Electronically adjustable Bragg filter module (FM) for setting the length of a Bragg filter (3), characterized in that a length measuring device (4) is provided for measuring the length or length change of the Bragg filter (3).
2. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach An- spruch 1, dadurch gekennzeichnet, daß als Längenmeßeinrichtung (4) mindestens ein Dehnungsmeßstreifen vorgesehen ist.2. Electronically adjustable Bragg filter module (FM) according to claim 1, characterized in that at least one strain gauge is provided as the length measuring device (4).
3. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach Anspruch 2, dadurch gekennzeichnet, daß ein Dehnungsmeßstreifen (4) vorgesehen ist, dessen Widerstand von der Längenänderung abhängig ist.3. Electronically adjustable Bragg filter module (FM) according to claim 2, characterized in that a strain gauge (4) is provided, the resistance of which is dependent on the change in length.
4. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach Anspruch 3, dadurch gekennzeichnet, daß ein weiterer Dehnungsmeßstreifen (14) zur Temperaturkom- pensation vorgesehen ist.4. Electronically adjustable Bragg filter module (FM) according to claim 3, characterized in that a further strain gauge (14) is provided for temperature compensation.
5. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach Anspruch 2, dadurch gekennzeichnet, daß als Längenmeßeinrichtung (4) ein Dehnungsmeßsensor vorgesehen ist, dessen Kapazität von der Längenänderung abhängig ist.5. Electronically adjustable Bragg filter module (FM) according to claim 2, characterized in that a strain gauge is provided as the length measuring device (4), the capacity of which is dependent on the change in length.
6. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß zur Längenänderung ein Piezoaktor (P) vorgesehen ist, der aus mehreren Piezoelementen (12) zusammengefügt ist, daß das Bragg-Filter (3) mit dem Piezoaktor (1) fest verbunden ist und daß mindestens ein Dehnungsmeßstreifen (4) mit dem Piezoaktor (1) und/oder dem Bragg-Filter (3) fest verbunden ist.6. Electronically adjustable Bragg filter module (FM) according to one of the preceding claims, characterized in that that a piezo actuator (P) is provided for changing the length, which is assembled from several piezo elements (12), that the Bragg filter (3) is firmly connected to the piezo actuator (1) and that at least one strain gauge (4) is connected to the piezo actuator ( 1) and / or the Bragg filter (3) is firmly connected.
7. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach Anspruch 6, dadurch gekennzeichnet, daß das Bragg-Filter (3) als Faser-Gitter realisiert ist.7. Electronically adjustable Bragg filter module (FM) according to claim 6, characterized in that the Bragg filter (3) is implemented as a fiber grating.
8. Elektronisch einstellbarer Bragg-Filtermodul (FM) nach Anspruch 7, dadurch gekennzeichnet, daß das Faser-Gitter in eine Nut des Piezoaktors (P) eingeklebt ist.8. Electronically adjustable Bragg filter module (FM) according to claim 7, characterized in that the fiber grating is glued into a groove in the piezo actuator (P).
9. Add-Drop-Modul (ADM) enthaltend eine Reihenschaltung mit mindestens einer Abzweigeeinrichtung (7), mindestens einem9. Add-drop module (ADM) containing a series connection with at least one branch device (7), at least one
Bragg-Filtermodul (FM1, FM2, FM3) und mindestens einer Einfügeeinrichtung (9), dadurch gekennzeichnet, daß das mindestens eine Bragg-Filtermodul (FM1, FM2, FM3) entsprechend einem der vorhergehenden Ansprüche ausgebildet ist.Bragg filter module (FM1, FM2, FM3) and at least one insertion device (9), characterized in that the at least one Bragg filter module (FM1, FM2, FM3) is designed in accordance with one of the preceding claims.
10. Einsteileinrichtung für Bragg-Filtermodule (FM) nach Anspruch 9, dadurch geke nzeichnet, daß eine Regelschaltung (11, 12, P, 3, 4) vorgesehen ist, die die Länge oder Längenänderung des Bragg-Filters (3) entsprechend einer Führungsgröße (F) konstant hält. 10. adjusting device for Bragg filter modules (FM) according to claim 9, characterized geke nzeich that a control circuit (11, 12, P, 3, 4) is provided, the length or length change of the Bragg filter (3) according to a reference variable (F) keeps constant.
11. Einsteileinrichtung nach Anspruch 10, dadurch gekennzeichnet, daß die Führungsgröße (F) von der Umgebungstemperatur (Tu) abhängig eingestellt wird. 11. One-piece device according to claim 10, characterized in that the reference variable (F) is set depending on the ambient temperature (Tu).
PCT/DE2000/001026 1999-04-13 2000-04-03 Adjustable bragg-grating filter module WO2000062118A1 (en)

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DE50000873T DE50000873D1 (en) 1999-04-13 2000-04-03 ADJUSTABLE BRAGG GRID FILTER MODULE
EP00931006A EP1166171B1 (en) 1999-04-13 2000-04-03 Adjustable bragg-grating filter module
AU49102/00A AU4910200A (en) 1999-04-13 2000-04-03 Adjustable bragg-grating filter module

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DE19916571A DE19916571A1 (en) 1999-04-13 1999-04-13 Adjustable Bragg grating filter module
DE19916571.8 1999-04-13

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DE102009022953A1 (en) * 2009-05-26 2010-12-02 Fachhochschule Jena Method and arrangement for determining the elongation or compression of a fiber optic grating

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EP1166171A1 (en) 2002-01-02
EP1166171B1 (en) 2002-12-04

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